BACKGROUNDMajor depressive disorder (MDD) is a well-known risk factor for suicidality, but depressed mood has been used non-specifically to describe the emotional state. We sought to compare influence of MDD versus sustained depressed mood on suicidality.

METHODSA total of 12,532 adults, randomly selected through the one-person-per-household method, completed a face-to-face interview using the Korean version of Composite International Diagnostic Interview (K-CIDI) and a questionnaire for lifetime suicidal ideation (LSI) and lifetime suicidal attempt (LSA).

RESULTSOf 12,361 adults, 565 were assessed as 'sustained depressed mood group' having depressed mood for more than two weeks without MDD (4.6%), and 810 adults were assessed as having full MDD (6.55%) which consisted of 'MDD with depressed mood group' (6.0%) and 'MDD without depressed mood group' (0.5%). The MDD with depressed mood group showed higher odds ratios for LSI and LSA than the sustained depressed mood group. Contrarily, no significant differences were found in LSI and LSA between the MDD group with and without depressed mood. MDD showed significant associations with LSI (AOR=2.83, 95%CI 2.12-3.78) and LSA (AOR=2.17, 95%CI 1.34-3.52), whereas sustained depressed mood showed significant associations with neither LSI nor LSA after adjusting for MDD and other psychiatric comorbidities. Interaction effect of sustained depressed mood with MDD was significant for LSI but not for LSA.

CONCLUSIONSSustained depressed mood was not related to LSI and LSA after adjusting for psychiatric comorbidities, whereas MDD was significantly associated with both LSI and LSA regardless of the presence of sustained depressed mood.